Four staff members at a nuclear power plant in Guangdong have been punished for breaching ­operational guidelines and trying to cover up the failures, the Ministry of Environmental Protection said this week, more than a year after the incident took place.

Three staff at the Yangjiang nuclear power plant in Guangdong, about 220km north of Hong Kong, were given administrative warnings, while the crew’s leader, Wei Haifeng, was stripped of his senior nuclear operator’s licence, a severe punishment.

Their actions caused a heat ­removal pump on one of the key reactors to stop functioning for six minutes at the plant, the first to go online in China after the 2011 ­Fukushima nuclear disaster in Japan. The operators then tried to cover up the incident by failing to log it as required, the ministry said.

The incident did not result in a radioactive leak or pose a direct public safety threat, two nuclear experts said.

According to the ministry, the breaches occurred on March 22, 2015 when the reactor was undergoing maintenance. The pump is a crucial part of the reactor’s water cooling system.

The plant’s developer, China General National Power Corp, told the South China Morning Post the incident did not affect plant safety because it occurred during maintenance. It also said it did “thorough analysis and a deep ­review” after the incident and initiated a “safety culture re-education” campaign among all staff.

The bigger safety issue is the breaching of regulations as an operator is required to report this to the regulatory body within a given time frame

Kai Ji-jung, City University

It said the incident was discovered during “self-assessment” in February and it reported it to the ministry’s nuclear safety bureau “in a timely manner” for sake of “credibility and transparency”.

But some experts warned the incident exposed human weaknesses in nuclear safety in China.

China has embarked on a ­nuclear power spree, aiming to develop 58 million kWh of nuclear power capacity by 2020 to ­account for 5 per cent of overall energy supplies.

It is also promoting its nuclear technology overseas.

Revealing further details about the incident, a former National Nuclear Safety Administration employee said that as soon as the pump stopped working due to the crew’s operational error, an alert popped up in the central control room. Controllers immediately contacted the maintenance crew, asking what happened. Meanwhile, backup pumps started to avoid dangerous overheating.

Wei, the crew leader who received the heaviest punishment, had worked more than a decade to earn his senior operator’s licence, a qualification that can cost millions of yuan to obtain. His experience should have prevented him or his subordinates from carrying out the “suicidal” operation which would almost guarantee the shutdown of the main pump, the expert said.

Why did they do this, that’s the question asked by many people in the industry

Industry expert

“Why did they do this, that’s the question asked by many people in the industry. Even a cadet would have known it could lead to severe consequences,” the expert said.

“Like captains in airlines, operators in nuclear power plants also receive regular mental health checks. If they are unhappy at work or at home, they must report it. None of them filed any reports.”

The ministry imposed the penalties on July 26 and posted a notice on its website on Tuesday.

Kai Ji-jung, chair professor of nuclear engineering at City University, said a residual heat ­removal pump was mainly used to cool the system as a backup in the case of an accident or power failure, so a six-minute stoppage under normal operations was not too big a technical safety issue.

“The bigger safety issue is the breaching of regulations as an operator is required to report this to the regulatory body within a given time frame,” he said.

“This reporting is required to ensure the quality of operations. A lot of small things being allowed to happen may indicate that there are problems with the operators.”

The Security Bureau said it was aware of the event but would not say if the plant informed the Hong Kong government.

Dr Raymond Ho Chung-tai, chairman of Guangdong Daya Bay Nuclear Power Station and Lingao Nuclear Power Station Nuclear Safety Consultative Committee, said such human errors needed to be rectified but his was a learning experience for the plant’s operators.

Xu Yuming, deputy secretary general of the China Nuclear Energy Association in Beijing, said the public reporting of the incident showed improved transparency on the government’s side.

“I think it is a good thing that the ministry reported the incident in a high-profile manner … It shows the government is serious about strengthening management of nuclear plants to improve safety standards.”

The notice about the punishment was among a series of administrative orders and notices published on its website. The ministry did not reply to requests for comment and information on Thursday.

Hu Xinmin, senior manager at Hong Kong-based electricity industry consultancy The Lantau Group, said: “Lessons should be learned from the Fukushima disaster, where post-accident investigations found that small procedural non-compliance incidents were not property reported to the national authority, contributing to a culture of complacency.”

Wang Biao, dean of the Sino-French Institute of Nuclear Engineering and Technology in Zhuhai, said: “It is normal that non-compliance incidences and their consequences are reported to the public this way, since safety is paramount from the government’s point of view. It must be noted that in every nuclear plant, there are multiple backup cooling pump systems, so even if one fails, the other systems will kick in to prevent any major problems.”

The Yangjiang nuclear power station went into commercial operation in March 2014. It was based on the CPR-1000 design found in most Chinese nuclear reactors commissioned since 2010.